Adds a modal for the pin/unpin message, based on the delete message modal.

How was this PR tested?

Tested locally with pinning/unpinning. As well as shift pin/unpin

Screenshots & Screencasts (if appropriate)

Checklist:

• I have carefully read the contributing guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR
• I have confirmed that any new dependencies are strictly necessary
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code

Please declare, if any, LLM usage involved in creating this PR

None
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